Quicker than Flashpoints due to no cutscenes/choices, and that you can get rid of adds with the Thermal Detonators (from Crates in the Mission). If the team works together it can go very quick.
Use the Rocket Launcher (from Crates) on Bosses.
Some maps (Dune and Dusted) even have pets you can use to make the fights even quicker.
Once you've done em a few times and know the layout and the mechanics and work as a team, you can speed through them quite quickly, with Thermal Detonators flying everywhere and whatnot.
There are also Mounts that can drop (From the chest in Fractured), i am sure there are other Mounts/things that can drop in the other Uprisings as well.
First time doing content , it can take some time since people do not know mechanics etc, but as more and more start to learn (if you play with randoms) or you and your friends get accustomed to the maps and the mechanics, you can zoom through them very quickly.
A quick way to gain some Command XP, and have fun with the friends.
My tip to you is to do Inferno and Fractured alot with guildies and friends.
You can complete Inferno or Fractured with a heavy DPS group (3 DPS 1 healer or all DPS) and complete them in 6-8 minutes for anywhere from 3000-4000 CXP/hr.